Presently, the types in head of windshield wiper arm are many in variety. Different type design of wiper arm head must be coordinated with its exclusive joint device to enable securely joint each other. Such as USA issued patents U.S. Pat. No. 6,516,491, U.S. Pat. No. 6,687,948, U.S. Pat. No. 6,782,581, U.S. Pat. No. 6,836,927, U.S. Pat. No. 6,836,926 and U.S. Pat. No. 6,910,244 as well as USA published patents S2004/0025280, US2005/0039292, US2004/0098821 and US2004/0117938, all disclosed their different types of wiper arm head in association with its exclusive joint device. In which, a conventional wiper arm with snap-on head disclosed in USA published patents US2005/0177970 is shown in the FIG. 1, FIG. 3 through FIG. 5. The head 2 is a hollow cuboid, which having a upward bent front tab 3 projecting on the head and having a pair of parallel and symmetrical bottom flap 4 downwards protruding at both vertical endwise sides of its central bottom end; an end brim 4a being formed at each said bottom flap 4 inwards said wiper arm 1 and a bottom edge 2a at said head 2 intersect in a acute included angle-θ (as shown in A view of the FIG. 1); The exclusive joint device in coordination with said conventional wiper arm 1 with snap-on head as shown in the FIG. 2 through FIG. 5 comprises a main body 10 and an upper gantry 20, where said main body 10, which is a cuboid, has an upper section vertical longitudinal side 11 with a spindle hole 12 perforating through at center and a lower section base with a pair of parallel insetting clip 13 inwards juxtaposing at both bottom brim such that said insetting clip 13 and said spindle hole in perpendicular configuration; said upper gantry 20, which is a hollow cuboid directly sheathing on the top surface and both said vertical longitudinal side 11 of said main body 10, has a snap-on hole 211 perforating at the junction of front section and middle section and a round hole 221 perforating at center of each middle section vertical lengthwise side as well as a pair of parallel juxtaposing elastic fin 24 projecting at rear end side 23 of each said vertical lengthwise side 22, in which a snap-on lug 25 is outwards protruded at each free end of said both elastic fin 24 such that a oblique top 251 being contrived between said snap-on lug 25 and the top surface of said elastic fin 24 as well as an oblique side 252 with angle equivalent to said included angle-θ being contrived at the junction of said snap-on lug 25 and the vertical outer side of said elastic fin 24 (as shown in S view of the FIG. 2).
Refer to FIG. 3 through FIG. 6, the rigging join method of said (conventional wiper arm 1 with snap-on head) and its exclusive joint device is described below, First, grip the central position of said elastic metal strip 7 on said wiper 6 by said insetting clip 13 at the bottom of said main body 10, then drive said fixing spindle 30 through said round hole 221 on said vertical lengthwise side 22 and said spindle hole 12 on said vertical longitudinal side 11 of said main body 10 respectively so that enable said upper gantry 20 to swivel tilt in some limit with said fixing spindle 30 of said main body 10 as pivot; Next, align and insert said front tab 3 on the front edge of said head 2 of said wiper arm 1 into said snap-on hole 211 on said front top surface 21 of said upper gantry 20 (as shown in the FIG. 4 and A view of the FIG. 6); then apply force on said wiper arm 1 in direction towards said upper gantry 20 so that said two bottom flaps 4 on said head 2 shove said snap-on lug 25 on said elastic fin 24 of said upper gantry 20 (as shown in B view of the FIG. 6); Lastly, by means of guiding function of said oblique top 251 on each said snap-on lug 25, said two bottom flaps 4 will synchronously securely snap-on said oblique side 252 of each said snap-on lug 25 (as shown in the FIG. 5 and A-A view of the FIG. 5) to finish the rigging joint of said wiper arm 1 and said wiper 6.
However, some drawbacks exist in the dismantling operation of said joint device from conventional wiper arm with (snap-on head) as below, Refer to FIG. 7 through FIG. 9, prior to the replacing a new wiper for said conventional wiper arm 1 with (snap-on head), an upwards force must be applied on wiper arm 1, which tightly stays on the windshield G in horizontal status (as shown in the FIG. 7); So that said wiper arm 1 is folded into vertical status together with said wiper 6 being separated away said windshield G in order to proceed the dismantling operation of worn wiper 6; The dismantling steps are described below:
a. Pinch two said snap-on lugs 25 on each said elastic fin 24 of said upper gantry 20 by the thumb and the forefinger of one hand to force two free ends of each said elastic fin 24 approach each other (as two arrow-heads shown in FIG. 9A); So that two said oblique sides 252 on each said snap-on lugs 25 are not snap-on confined by two said bottom flaps 4 on said head 2 any longer;
b. Hold said wiper arm 1 by another hand to apply force towards away of said upper gantry 20 in order to let said two bottom flaps 4 on said head 2 of said wiper arm 1 separate off two said elastic fins 24 on said upper gantry 20 (as shown in FIG. 9B);
c. Continuously separate said upper gantry 20 off said wiper arm 1 until said front tab 3 on said head 2 being not contact with the inner wall of said front top surface 21 on said upper gantry 20 any longer; so that let said front tab 3 get rid of the confinement of said snap-on hole 211 in order to finish the dismantling operation of worn wiper 6 off said wiper arm 1 now (as shown in FIG. 9C).
However, there are some drawbacks in aforementioned dismantling operation of worn wiper 6 as below, First, in step a, the maimed person handicapped without thumb, forefinger or middle finger is unable to force said two elastic fins 24 approach each other to get rid of the snap-on confinement by two said bottom flaps 4 (only one said elastic fin 24 being inwards compressed does not enable to separate off two said bottom flaps 4 as another said elastic fin 24 being still snapped). Such contrivance rather discriminates against the maimed person for not taking account of them. Next, there is no subsidiary fixing design with said elastic fin 24. Due to weakening elasticity caused from attachment of improper foreign matter or external force collision as well as aging by weathering, said elastic fin 24 might automatically separate off said two bottom flap 4 on said head 2 unexpectedly and hurt the surface of the windshield G eventually (it always happens in high speed swing of wiper arm adjustment during snowstorm).